At the present time, there exist numerous types of valves for occluding or redirecting fluid flow in catheters and intravenous (I.V.) tubes which are commonly used in hospitals and other medical facilities. Because catheters and I.V. tubes necessarily create openings to the internal organs of the body, it is of the utmost importance to maintain a closed, sterile system while these instruments are in place. To this end, valves for occluding fluid flow in I.V. lines are sometimes incorporated within the lumen of the tube to maintain the integrity of the fluid system and prevent airborne contaminants from entering the body. One type of valve well known in the art obstructs fluid flow using a ball in the lumen of the fluid line which snugly fits against the inner walls of the tube. Under normal conditions, such a valve is closed because the tight seal between the ball and the tube completely occludes fluid flow. To open the valve, the tube can be pinched or otherwise deformed to allow flow around the ball, without compromising the sealed interior of the system. Once the pinching pressure is withdrawn, the tube automatically reforms around the ball, to again impede flow. These so-called "ball valves" are generally practical for such intermittent use as collecting small samples of urine from catheters. For a more continuous usage, such as when patients are infused intravenously, it is necessary to maintain a valve in its open, or "free flow", position for extended periods of time. Ball valves generally cannot be kept open for extended periods of time, however, because the plastic tube surrounding the ball tends to permanently deform. Once the tube loses its original shape, a permanent "free flow" condition exists since the ball valve cannot properly reseat to close the fluid line. Ball valves are, however, easy to use and relatively easy to manufacture. Thus, they are desirable for use where possible. For example, a simple ball valve in an I.V. line would permit periodic changes of fluid source, for a patient requiring a continuous flow of medication, without having to change the entire I.V. line each time the solution bag is replaced.
The present invention recognizes the need for an I.V. tube ball valve which can open for extended periods of time, yet maintain its ability to properly reseal. Therefore, the present invention provides a ball valve assembly which can be pinched or otherwise positioned in a free flow condition for extended periods of time without permanently deforming the original shape of the tube. Further, the present invention provides an I.V. tube valve which can be used manually or in conjunction with a pump for extended use. Additionally, the present invention provides a ball valve assembly which is easy to use, relatively inexpensive to manufacture and comparatively cost-effective.